Fluid delivery system

ABSTRACT

A fluid delivery system ( 1 ) includes a reservoir ( 7 ) for storing a fluid, a pumping chamber ( 8 ) and an actuator ( 20 ). The pumping chamber ( 8 ) has a volume, an inlet valve ( 48 ) providing selective fluid communication between the pumping chamber volume and the reservoir, an outlet valve ( 49 ), and a membrane ( 47 ) the displacement of which changes the pumping chamber volume. The actuator ( 20 ) moves a drive member ( 21 ) in reciprocating motion. The actuator ( 20 ) is disposed in a housing ( 9 ) having an aperture ( 36 ) from which the drive member projects. The reservoir ( 7 ) and the pumping chamber ( 8 ) are arranged in a cartridge ( 3 ) removably attachable to the housing. When the cartridge ( 3 ) is attached to the housing ( 9 ) the drive member ( 20 ) is operatively coupled to the pumping chamber membrane ( 47 ). The fluid delivery system may be applied to an infusion system for the infusion of a liquid therapeutic product, such as insulin.

FIELD OF THE INVENTION

The present invention relates to a fluid delivery system and to aninfusion system for the infusion of a liquid therapeutic product.

BACKGROUND OF THE INVENTION

Infusion systems for the infusion of liquid therapeutic products intothe human or animal body are known in the art, e.g. from U.S. Pat. No.4,395,259. Such systems are particularly, though not exclusively,intended for the infusion of insulin into the body for diabetes therapy.The system has an infusion device which may be implanted or wornexternally on the body, and a remote controller that can wirelesslymonitor the function of the infusion device. The infusion deviceincludes a pump, a reservoir of the therapeutic product, controlelectronics and a battery power supply.

Such devices tend to be relatively large in size and have a highelectrical power requirement necessitating frequent replacement orrecharging of the battery. Extended or frequent periods where a usercannot receive delivery of the therapeutic product due to refilling orreplacement of the reservoir of therapeutic product, or replacement orrecharging of the battery are undesirable from a medical standpoint andare inconvenient for the user.

Moreover, the wetted parts of the infusion device in contact with theliquid therapeutic product require periodic flushing or replacement.Whilst disposable reservoirs are known, their interface with the pumppart of the infusion device tends to result in a complex, costlysolution having a high electrical power requirement to achieve theaccuracy required for the delivery of medication at flow rate incrementsin the region of 25 to 50 nano litres per hour. More recentlydisposable, or semi disposable pump designs have become available butminimising the cost of any disposable parts of the device still presentsa significant barrier.

SUMMARY OF THE INVENTION

A first aspect of the invention provides a fluid delivery systemcomprising: a reservoir for storing a fluid; a pumping chamber having avolume, an inlet valve providing selective fluid communication betweenthe pumping chamber volume and the reservoir, an outlet valve, and amembrane the displacement of which changes the pumping chamber volume;and an actuator for moving a drive member in reciprocating motion,wherein the actuator is disposed in a housing having an aperture fromwhich the drive member projects, and wherein the reservoir and thepumping chamber are arranged in a cartridge removably attachable to thehousing such that when the cartridge is attached to the housing thedrive member is operatively coupled to the pumping chamber membrane.

A further aspect of the invention provides an infusion system for theinfusion of a liquid therapeutic product comprising the fluid deliverysystem according to the first aspect. The infusion system may furthercomprise an infusion set coupled to the outlet valve, either directly orvia an infusion tube.

In operation of the fluid delivery system, the pumping chamber volumefills with fluid when the inlet valve is opened, the outlet valve isclosed, and the membrane moves to increase the volume of the pumpingchamber. The pumping chamber volume empties (all or a portion of thefluid contained therein) when the inlet valve is closed, the outletvalve is opened, and the membrane moves to decrease the volume of thepumping chamber.

The term ‘selective fluid communication’ is used here to refer to theselective creation and disruption of a fluid path depending on the stateof the valve. When the valve is opened the fluid path is created. Whenthe valve is closed the fluid path is disrupted.

The ‘reciprocating drive member’ is used here to refer to any drivecomponent that moves back and forth in linear motion and may, forexample, be a piston. The piston may be a cylinder which extends throughthe aperture in the housing. Alternatively, the drive member may be adisc or other component driven by a rotatable cam, where the cam extendsthrough the aperture in the housing such that the drive member remainson the side of the aperture opposite the actuator. The reciprocatingdrive member may be rigid, or may form part of a flexible membranecovering the aperture. The aperture is preferably sealed. The drivemember may be sealed within the aperture, or alternatively the drivemember may be sealed beneath a membrane covering the aperture. In thisway the drive member is said to project from the aperture regardless ofwhether the drive member moves the sealed boundary of the housing.

The term ‘cartridge’ is used here to refer to any fluid container forready connection to and disconnection from the housing. The housing mayhave a recess into which the cartridge sits, or the cartridge may beflush mounted on the housing. The cartridge may be attached to thehousing by any means, preferably by securely retaining the cartridge tothe housing, e.g. by a snap fit, screw fit or other mechanicalconnection that allows ready detachment.

The infusion system comprising the fluid delivery system may be adaptedfor the infusion of one of a variety of liquid therapeutic products. Inone application the infusion system is an insulin infusion system forcontinuous subcutaneous insulin infusion therapy.

The invention is advantageous in that the wetted parts of the system areall contained within the removable cartridge, whilst the actuator isseparately contained within the housing. Also, the passive parts of thefluid pump are all within the cartridge whilst the active parts of thepump are within the housing. In this way the cartridge may beconstructed inexpensively enabling the cartridge to be a disposable partof the system, whilst the actuator can be housed within a durable partof the system.

The actuator may include a wedge shaped member operatively coupled tothe drive member, the wedge shaped member being moveable with respect tothe drive member to convert reciprocating linear motion of the wedgeshaped member along a first axis to reciprocating linear motion of thedrive member along a second axis substantially perpendicular to thefirst axis.

The actuator may include a lever rotatable about a pivot point, and thedrive member is operatively coupled to the lever.

The lever may have a distal end opposite the pivot point, and the distalend of the lever may be operatively coupled to the wedge shaped member.The drive member may be disposed between the pivot point and the wedgeshaped member, and may be disposed closer to the pivot point than to thewedge shaped member.

The actuator may include a shape memory material operatively coupled tothe wedge shaped member.

The shape memory material may have a first shape corresponding to afirst position of the wedge shaped member along the first axis, and asecond shape corresponding to a second position of the wedge shapedmember along the first axis.

The shape memory material may be a shape memory alloy. The shape memoryalloy may be a resistance heating shape memory alloy, such as a Nitinolalloy (Nickel-Titanium in approximately a 1:1 ratio). The shape memorymaterial may be formed as a wire, e.g. a muscle wire.

The actuator may include a biasing element for biasing the wedge shapedmember to a first position along the first axis. The biasing element maybe a spring, e.g. a compression spring.

The housing aperture may be sealed by a flexible aperture membrane overthe drive member.

The aperture membrane may be sufficiently resilient to bias the drivemember towards the housing.

The aperture membrane may comprise a resilient elastomeric material.

The aperture membrane may contact the pumping chamber membrane when thecartridge is attached to the housing.

The pumping chamber membrane is sufficiently resilient to bias the drivemember towards the housing when the cartridge is attached to thehousing.

The pumping chamber membrane may comprise a resilient elastomericmaterial.

The inlet valve and the outlet valve may each comprise a normally closedone-way check valve. The inlet valve may have an inlet side and anoutlet side. The outlet valve may have an inlet side and an outlet side.

The one-way valves may each comprise a conical valve seat, and amembrane having a hole that is located around the conical valve seat,such that a surface of the valve seat seals onto an inner periphery ofthe hole in the membrane whereby the membrane can be deflected from thesurface of the valve seat under fluid pressure to provide a fluid pathacross the membrane and allowing fluid to flow from one side of themembrane to the other.

The inlet side of the inlet valve may be selectively fluidicallyconnected to the reservoir. The outlet side of the inlet valve may befluidically connected to the inlet side of the outlet valve, e.g. viathe pumping chamber volume.

The pumping chamber membrane may be fluidically connected to the outletside of the inlet valve. The pumping chamber membrane may be disposedadjacent the outlet side of the inlet valve.

The cartridge may be a disposable part of the system having an intendedlifetime less than that of the actuator.

The fluid delivery system may further comprise a power source forsupplying electrical energy to the actuator, and a controller forcontrolling the actuator. The power source and the controller may bewithin the housing. The power source may be a rechargeable battery. Thecontroller may provide wireless communication to a remote handset.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to theaccompanying drawings, in which:

FIG. 1 illustrates a wearable part of an external infusion system;

FIG. 2 illustrates a handset of the infusion system for wirelesscommunication with the wearable part;

FIG. 3 illustrates a durable pump part of the infusion system;

FIG. 4 illustrates the durable pump part with its cover removed;

FIG. 5 shows a cutaway view of the actuator for the pump;

FIG. 6 shows a plan view of the cartridge;

FIG. 7 shows a front view of the cartridge; and

FIG. 8 shows in detail the inlet and outlet valves of the pumpingchamber part of the cartridge.

DETAILED DESCRIPTION OF EMBODIMENT(S)

FIG. 1 shows the wearable part of an external infusion system 1 for thecontinuous subcutaneous infusion of insulin into the human body throughrepetitive small pulses of infusion. The infusion system 1 comprises apump part 2, a cartridge 3 having an outlet port 4 connected to aninfusion set 5 via an infusion tube 6.

The infusion set 5 includes a subcutaneous cannula and an adhesive mountfor adhering the infusion set to the patient's skin. The cannula istypically made of flexible plastic so as not to cause discomfort for thepatient during use. The infusion set is typically installed into aspring loaded insertion device together with a steel needle surroundingthe cannula. Upon insertion, the steel needle is removed leaving thecannula in place. Alternative infusion sets, which may replace theinfusion set shown in FIG. 1, comprise a steel needle instead of thecannula.

Depending on the desired positioning of the pump part 2 with respect tothe infusion set 5 during use the length of the infusion tube 6 may belonger or shorter than that shown in FIG. 1, and indeed the infusion set5 may be coupled directly to the output port 4 of the pump where closecoupling of the infusion set 5 and the pump part 2 is desired, therebyavoiding the need for the flexible infusion tube 6.

The cartridge 3 includes a reservoir 7 for storing a supply of insulinand a pumping chamber 8. The pump part 2 contains an actuator, arechargeable battery power supply and control electronics forcontrolling the actuator.

The cartridge 3 is removably attachable to a housing 9 of the pump part2 such that when the cartridge 3 is attached to the housing 9 a drivemember of the actuator is operatively coupled to the pumping chamber 8for delivering a supply of insulin from the reservoir 7 to the outletport 4 and into the infusion set 5 via the infusion tube 6.

The control electronics of the pump part 2 includes a transceiver forwireless communication with a user control handset 10 shown in FIG. 2.The handset 10 also includes a transceiver for wireless communicationwith the pump part 2. The wireless communication may be via Bluetooth^(TM) or other radio frequency near field communication means. Thehandset 10 includes a graphical user interface 11 and a tactile userinterface 12. The handset 10 enables a user to perform the followingfunctions:

-   -   Define and store basal profiles;    -   Transfer an active basal profile to the pump 2;    -   Define and transmit a bolus request to the pump 2;    -   Define and transmit a temporary basal to the pump 2;    -   View a graphical recommendation of a bolus based on glucose        readings from a separate blood glucose meter or entered manually        following a blood glucose meter reading from a separate blood        glucose meter (not shown);    -   View graphically pump performance over time;    -   Request the current status of the pump 2 (including what insulin        delivery is currently in progress, battery status, alarm        conditions, insulin reservoir level, etc).

The handset 10 is also enabled for internet connectivity, e.g. by awireless radio connection such as Bluetooth™ or Wi-Fi between thehandset and remote internet connected devices. The internet connectivityenables two-way patient support either directly or via an intermediateinternet connected device such as a PC, laptop or mobile device.

Turning next to FIGS. 3 to 5 the pump part 2 will now be described indetail. As shown in FIGS. 3 and 4 the pump part 2 includes an actuator20 for driving a drive member 21 in reciprocating motion. The housing 9also contains a printed circuit board 13 carrying the controlelectronics, a piezo-electric sounder 14, a chassis 15 for supportingthe actuator 20, the PCB 13, the piezo-electric sounder 14 and defininga battery holder 16 for receiving a rechargeable battery (not shown). InFIG. 4 a top cover 17 (visible in FIG. 3) has been removed for clarity.As best shown in FIG. 3, the chassis 15 defines a recess 18 forreceiving the cartridge 3. In FIG. 3 the pump 2 is shown with thecartridge 3 removed. The pump part 2 and the cartridge 3 havecooperating retaining features 19 a, 19 b for the secure retention andready removal of the cartridge 3 from the pump part 2 using a snap fittype connection.

FIG. 5 illustrates the actuator 20 in detail. The actuator 20 includes alever 22 having a proximal end 23 and a distal end 24 opposite theproximal end 23. The lever 22 is rotatable about a pivot point 25 at itsproximal end 23. Drive member 21 is formed as a generally cylindricalpiston operatively coupled to the lever 22. The drive member 21 isdisposed spaced from the pivot point 25 and is disposed nearer theproximal end 23 than to the distal end 24 of the lever 22. The actuator20 further comprises a slider 26 having a wedge shaped member 27. Theslider 26 is in sliding contact with a runner 28. The slider 26 is insliding contact with the runner 28 and moves with respect to the runner28 along an axis X. A compression spring 29 biases the slider 26 in thedirection of arrow X1 against an end stop (not shown) to a firstposition.

A shape memory alloy actuator 30, which in the illustrated embodiment isa Nitinol muscle wire, is securely retained at one end to the slider 26and is securely retained at its other end by a crimp assembly 31. Thecrimp assembly 31 is electrically conductive and is electricallyconnected to a first terminal 32. The slider 26 is electricallyconductive and forms an electrically conductive sliding contact with therunner 28. The runner 28 is electrically connected to a second terminal33.

The distal end 24 of the lever 22 has an inclined surface 34 whichcontacts an inclined surface 35 of the wedge shaped member 27. Theinclined surfaces 34, 35 are inclined with respect to axis X. In FIG. 5the actuator 20 is depicted in a first position in which the slider 26is biased in the direction of arrow X1 to the first position in whichthe lever 22 is pivoted about pivot point 25 away from the runner 28. Aunique property of an Nitinol shape memory alloy is its superelasticity. Under the action of the compression spring 29 the Nitinolmuscle wire 30 is deformed by elastic strain such that the length of themuscle wire 30 between its crimped ends is significantly longer than inits un-deformed, as manufactured, state.

When an electric current is passed between the terminals 32 and 33 anelectrical connection is made via the crimp assembly 31, the Nitinolmuscle wire 30, the slider 26, and the runner 28. Due to the smalldiameter of the Nitinol muscle wire 30, the Nitinol muscle wire 30undergoes resistance heating which causes the Nitinol muscle wire 30 toheat up and recover its original, un-deformed shape which shortens thelength of the Nitinol wire 30 between its crimped ends, thus moving theslider 26 in the direction of arrow X2 against the bias of thecompression spring 29.

This movement of the slider 26 causes relative sliding movement of theinclined surfaces 35 and 34 of the wedge shaped member 27 and the distalend 24 of the lever 22 such that the lever 22 pivots about the pivotpoint 25 to move the lever 22 towards the runner 28. This in turn movesthe drive member 21 in the direction of arrow Y2 along axis Y which liessubstantially perpendicular to axis X.

When current ceases to flow between the terminals 32 and 33 theresistance heating of the Nitinol muscle wire 30 is stopped and as themuscle wire cools the compression spring 29 causes the muscle wire 30 toonce again deform under super elasticity and the slider 26 moves in thedirection of arrow X1, causing rotation of the lever 22 about pivotpoint 25 and corresponding movement of the drive member 21 in thedirection of arrow Y1.

In this way the cyclic heating and cooling of the Nitinol muscle wire30, by switching on and off an electric current between the terminals 32and 33, causes the drive member 21 to move along axis Y in reciprocatingmotion in the direction of arrows Y1 and Y2. The selective opening andclosing of the circuit between the terminals 32 and 33 is effected bythe control electronics of the printed circuit board 13 with theelectrical energy being provided by the battery (not shown).

Reverting to FIG. 3, showing the pump part 2 with the cartridge 3removed, the drive member 21 can been seen in an aperture 36 in thehousing 9. The drive member 21 is covered by a membrane 37. The membrane37 is an elastomeric membrane stretched over a head 38 of the drivemember 21. The membrane 37 performs two functions. Firstly, membrane 37ensures the housing 9 is fluid tight to protect the electricalcomponents therein. Secondly, the membrane 37 provides a biasingfunction to the drive member 21 to bias the drive member 21 in thedirection of arrow Y2. The membrane 37 applies a force in the directionof arrow Y2 throughout the full range of reciprocating motion of thedrive member 21.

When the Nitinol muscle wire 30 is heated to cause the Nitinol musclewire to contract and move the slider 26 in the direction of arrow X2,relative sliding movement between the inclined surfaces 34 and 35 occursand the membrane 37 urges the drive member 21 to move in the directionof arrow Y2 forcing the lever 22 to pivot about pivot point 25. In thisway the membrane 37 forms a part of the actuator 20. When the Nitinolmuscle wire 30 cools down and the slider 26 under the restoring force ofthe spring 29 returns to the first position against the end stop (notshown) the drive member 21 is in its fully extended position havingmoved in the direction of arrow Y1 so as to stretch the membrane 37 toits full extent.

Turning next to FIGS. 6 to 8 the cartridge 3 will now be described indetail. As shown in FIG. 6 the cartridge 3 includes a reservoir case 38containing the reservoir 7 for storing a supply of insulin. Thereservoir 7 is formed as a rectangular frame 39 with front and rear filmcovers welded onto the frame so as to bound the fluid volume of thereservoir 7. The reservoir 7 fits within the case 38 which providesstructural support and protection for the reservoir 7.

At one corner the case 38 includes a filling aperture 41 for receiving afilling needle. Beneath the aperture 41 is a rubberised insert 42 whichcovers and seals an inlet port 43 of the reservoir 7 passing through thereservoir frame 39. The needle tip penetrates the seal member 42. Byconnecting a supply of insulin under positive pressure to the fillingneedle the insulin may be injected through the needle into the inletport 43 of the reservoir 7 so as to fill the reservoir with insulin. Thereservoir frame 39 also includes an outlet port 44 in fluidcommunication with a pump stack indicated generally by reference number45.

The pump stack 45 includes a valve assembly 46, the pumping chamber 8having a pumping chamber membrane 47 and the outlet port 4. FIG. 7illustrates a front view of the cartridge 3 in detail showing the frontface of the pump stack 45, and FIG. 8 illustrates the valve assembly 46in more detail. The valve assembly 46 includes an inlet valve 48 and anoutlet valve 49. The inlet valve 48 has an inlet side 50 fluidicallyconnected via the inlet port 54 to the reservoir 7. Inlet valve 48 alsohas an outlet side 51 which opens into the pumping chamber 8. Thepumping chamber membrane 47 has a front face 52 and a rear face 53,where the rear face 53 forms a boundary to the pumping chamber 8 suchthat the displacement of the membrane 47 changes a volume of the pumpingchamber 8. The pumping chamber membrane 47 sits adjacent the outlet side51 of the inlet valve 48.

The pumping chamber 8 also comprises a fluid passage 8 a extendingbetween the outlet side 51 of the inlet valve 48 and an inlet side 53 ofthe outlet valve 49. The outlet valve 49 also has an outlet side 54fluidly connected via conduit 55 to the outlet port 4.

The inlet valve 48 and the outlet valve 49 are each one-way check valvesand include an annular elastomeric valve member 60 over a conical valveseat 61 such that the conical valve seat 61 projects through the hole inthe centre of the annular valve member 60. The outer periphery of thevalve member 60 is fixed—by bonding or clamping, for example—within thepump stack 45. The conical valve seat 61 is projected through the holein the valve member 60 so that the inner periphery of the elastomericvalve member is deflected by the valve seat 61 and the valve seat 61forms a seal around the inner periphery of the annular valve member.More particularly, the conical valve seat 61 seals onto an edge of theinner periphery of the hole in the annular valve member.

The sealing is sufficient to prevent flow of fluid from the inlet sideto the outlet side of the respective valve unless the pressure on theinlet side is higher that the pressure on the outlet side and thedifference exceeds the breakthough pressure of the valve by providingsufficient force to partially and temporarily lift the valve membrane 60away from the valve seat 61. The force required to lift the valve member60 away from the valve seat 61 is the extent to which the valve member60 is deflected by the valve seat 61, the stiffness of the elastomericvalve seat 60 and the surface finish on the valve seat 61. By carefullycombining these features, micro valves can be fabricated with differentbreakthrough pressures.

During filling of the reservoir 7 with fluid, in this case insulin, thefluid is injected under positive pressure sufficient to exceed thebreakthrough pressure of the inlet valve 48, which may be set atapproximately 100 millibars. In practice, the breakthrough pressure maybe in the range of approximately 10 millibars to approximately 500millibars, preferably between approximately 50 millibars toapproximately 300 millibars. This equates to a relatively low tension inthe elastomeric valve member 60 of typically less than 1 Newton.

When the pressure in the reservoir 7 during filling exceeds thebreakthrough pressure of the inlet valve 48, fluid flows from thereservoir 7 through the reservoir outlet port 44 and into the pumpingchamber 8 and starts to build pressure on the inlet side of the outletvalve 49. Once the positive pressure differential between the inlet sideand the outlet side of the outlet valve 49 exceeds the breakthroughpressure of the outlet valve 49 the outlet valve 49 opens and fluidpasses via conduit 55 to the outlet port 4 of the cartridge 3. With theinfusion tube 6 and infusion set 5 connected to the outlet port 4 of thecartridge 3 insulin flows to the infusion set 5 expelling air in theinfusion tube 6 and the infusion set 5 until the insulin begins to exitthe infusion set 5 indicating that the reservoir 7 is full and theinfusion set 5 is primed ready for use.

At this point the injection of insulin through the filling needle intothe filling aperture 41 can be stopped, and the pressures in thereservoir 7 will return to ambient causing the inlet valve 48 and theoutlet valve 49 to close leaving a positive pressure in the valveapparatus 46. Removal of the filling needle from the filling aperture 41causes the seal insert 42 to seal the reservoir 7 to prevent escape ofinsulin from the filling aperture 41. The filled and primed cartridge 3having the infusion set 5 connected is now ready for coupling to thepump part 2.

As explained above the drive member 21 of the actuator 20 rests in afully extended position in the direction of arrow Y1 in FIG. 5 such thatupon installation of the cartridge 3 in the pump part 2 the aperturemembrane 37 stretched over the head 38 of the drive member 21 directlycontacts that front face 52 of the pumping chamber membrane 47 so as todeflect the pumping chamber membrane 47 inwardly into the pumpingchamber 8 thereby decreasing the volume of the pumping chamber 8. Thestretched membrane may achieve a tension of approximately 2 Newtons. Inother embodiments the drive member 21 is biased by another component,such as a spring in the actuator 20 or a membrane in the cartridge 3 forexample, which may be used in addition to or instead of the biasingfunction of the membrane 27. Since the pumping chamber 8 is fully filledwith insulin (i.e. there are no gas bubbles which may cause a fluidfront) the pressure in the pumping chamber temporarily increases at theinlet side 53 of the outlet valve 49 which opens releasing a very smallvolume of insulin from the outlet valve 49 which exits via the outletport 4 and from the infusion set 5. This displacement of the pumpingchamber 8 is of the order of 10 microlitres or less and preferably is2.5 microlitres or less.

By successively energising the Nitinol muscle wire 30 the drive member21 of the actuator 20 is caused to move in reciprocating motion in thedirections of arrows Y1 and Y2 along axis Y which, by displacement ofthe pumping chamber membrane 47, causes successive opening and closingof the inlet valve 48.

When the Nitinol muscle wire 30 is heated the drive member 21 retractsin the direction of arrow Y2 causing the pumping chamber membrane 47 topartially relax out from the pumping chamber which increases the volumeof the pumping chamber and thereby decreases the pressure in the pumpingchamber 8 such that the positive pressure differential between the inletside 50 and the outlet side 51 of the inlet valve 48 increases above thebreakthrough pressure of the inlet valve so that the inlet valve 48opens and the pumping chamber 8 fills with insulin from the reservoir 7.

Subsequent cooling of the Nitinol muscle wire 30 causes the drive member21 of the actuator 20 to extend in the direction of arrow Y1 stretchingthe pumping chamber membrane 48 into the pumping chamber which decreasesthe volume of the pumping chamber 8 and thereby increases the pressurein the pumping chamber 8 until the positive pressure differentialbetween the inlet side 53 and the outlet side 54 of the outlet valve 49increases above the breakthrough pressure of the outlet valve 49 wherebythe outlet valve 49 opens and insulin flows through the outlet valve andvia the outlet port 4 to the infusion set 5 for delivery of insulin tothe patient.

Using the handset 10 the control electronics in the circuit board 13 ofthe pump part 2 may be controlled to activate the actuator 20 to providethe required delivery profile of insulin to the patient.

The cartridge 3 may be exchanged for a full cartridge when empty andrefilled as described above.

Although the invention has been described above with reference to one ormore preferred embodiments, it will be appreciated that various changesor modifications may be made without departing from the scope of theinvention as defined in the appended claims.

1. A fluid delivery system comprising: a reservoir for storing a fluid;a pumping chamber having a volume, an inlet valve providing selectivefluid communication between the pumping chamber volume and thereservoir, an outlet valve, and a membrane the displacement of whichchanges the pumping chamber volume; and an actuator for moving a drivemember in reciprocating motion, wherein the actuator is disposed in ahousing having an aperture from which the drive member projects, andwherein the reservoir and the pumping chamber are arranged in acartridge removably attachable to the housing such that when thecartridge is attached to the housing the drive member is operativelycoupled to the pumping chamber membrane.
 2. A fluid delivery systemaccording to claim 1, wherein the actuator includes a wedge shapedmember operatively coupled to the drive member, the wedge shaped memberbeing moveable with respect to the drive member to convert reciprocatinglinear motion of the wedge shaped member along a first axis toreciprocating linear motion of the drive member along a second axissubstantially perpendicular to the first axis.
 3. A fluid deliverysystem according to claim 1, wherein the actuator includes a leverrotatable about a pivot point, and the drive member is operativelycoupled to the lever.
 4. A fluid delivery system according to claim 2,wherein the lever has a distal end opposite the pivot point, and thedistal end of the lever is operatively coupled to the wedge shapedmember.
 5. A fluid delivery system according to claim 2, wherein theactuator includes a shape memory material operatively coupled to thewedge shaped member.
 6. A fluid delivery system according to claim 5,wherein the shape memory material has a first shape corresponding to afirst position of the wedge shaped member along the first axis, and asecond shape corresponding to a second position of the wedge shapedmember along the first axis.
 7. A fluid delivery system according toclaim 6, wherein the shape memory material is a shape memory alloy,preferably a resistance heating shape memory alloy such as a Nitinolalloy.
 8. A fluid delivery system according to claim 2, wherein theactuator includes a biasing element for biasing the wedge shaped memberto a first position along the first axis.
 9. A fluid delivery systemaccording to claim 1, wherein the housing aperture is sealed by aflexible aperture membrane over the drive member.
 10. A fluid deliverysystem according to claim 9, wherein the aperture membrane issufficiently resilient to bias the drive member towards the housing. 11.A fluid delivery system according to claim 9, wherein the aperturemembrane comprises a resilient elastomeric material.
 12. A fluiddelivery system according to claim 9, wherein the aperture membranecontacts the pumping chamber membrane when the cartridge is attached tothe housing.
 13. A fluid delivery system according to claim 12, whereinthe pumping chamber membrane is sufficiently resilient to bias the drivemember towards the housing when the cartridge is attached to thehousing.
 14. A fluid delivery system according to claim 1, wherein thepumping chamber membrane comprises a resilient elastomeric material. 15.A fluid delivery system according to claim 1, wherein the inlet valveand the outlet valve each comprise a normally closed one-way checkvalve.
 16. A fluid delivery system according to claim 1, wherein theinlet valve has an inlet side and an outlet side, and the outlet valvehas an inlet side and an outlet side, the inlet side of the inlet valveis selectively fluidically connected to the reservoir, and the outletside of the inlet valve is fluidically connected to the inlet side ofthe outlet valve.
 17. A fluid delivery system according to claim 16,wherein the pumping chamber membrane is fluidically connected to theoutlet side of the inlet valve.
 18. A fluid delivery system according toclaim 1, wherein the cartridge is a disposable part of the system andhas an intended lifetime less than that of the actuator.
 19. A fluiddelivery system according to claim 1, further comprising a power sourcefor supplying electrical energy to the actuator, and a controller forcontrolling the actuator, wherein the power source and the controllerare within the housing.
 20. An infusion system for the infusion of aliquid therapeutic product comprising a fluid delivery systemcomprising: a reservoir for storing a fluid; a pumping chamber having avolume, an inlet valve providing selective fluid communication betweenthe pumping chamber volume and the reservoir, an outlet valve, and amembrane the displacement of which changes the pumping chamber volume;and an actuator for moving a drive member in reciprocating motion,wherein the actuator is disposed in a housing having an aperture fromwhich the drive member projects, and wherein the reservoir and thepumping chamber are arranged in a cartridge removably attachable to thehousing such that when the cartridge is attached to the housing thedrive member is operatively coupled to the pumping chamber membrane. 21.An infusion system according to claim 20, further comprising an infusionset fluidically coupled to the outlet valve.